Sensitive relay



G. M. PAHUD SENSITIVE RELAY Feb. 26, 1963 2 Sheets-Sheet 1 Filed Oct. 28, 1960' FIG.5

INVENTOR. George M. PAHUD WMSW ATTORNEYS Feb. 26, 1963 e. M. PAHUD SENSITIVE RELAY 2 Sheets-Sheet 2 Filed 001.. 28, 1960 FIG.?

III/I INVENTOR. GeorgeMPohud wh z/um MIC n ATTORNEYS aired dtates harem? dice Fatented Feb. 26, 19 33 3,07%,478 SENSETEVE RELAY George M. Pahud, Needham, Mass, assignor to Sigma Instruments, inc, a corporation of Massachusetts Filed Oct. 28, 1%0, Ser. No. 65,645 '7 Claims. ((11. ZtNL-MM) This invention relates to electromagnetic structures, and more particularly to structures which are suitable for use as relays of the polarized type. This invention is related to that disclosed in United States patent application Serial No. 731,935 filed April 30, 1958, now Patent No. 2,960,583.

The present invention finds special applicability in the field of micro-miniature relays where very high sensitivity coupled with positive action and resistance to shocks is of the utmost importance. In relays of this type which must be responsive to very small current changes, frictional resistance to armature movement is a very important factor. An object of the present invention is to practically eliminate frictionby utilizing a crossed spring fiexure mounting for the armature. The flexure springs also provide the spring biasing forces, which need be very slight. The flex-ure springs are also preferably electrically insulated from the armature and extended so as to form the contact blades. This results in avery eiiective and simplified ructure having a'rnini'murn number of parts. Owing to thepr'actically frictionless mounting of the armature'it is p'ojssibleto produce an electromagnetic device havingspring force characteristics which allow a much more efficient use of the magnetic forces and consequently great sensitivity in terms of power requirements.

The mounting ofthe armature on a flexure pivot construction allows great flexibility of adjustment, since the armature gaps can be changed during final assembly of the structure, permitting both the area of the gap and the length of the gap to be under the control of the adjuster. Owing to the elimination of ball or pivot bearings, the mechanical life of the relay will be much greater. Costs are also kept to a minimum, and elimination of friction in the bearings assures reliable snap action of the switch contacts. Other and further objects and advantages of the invention will appear in the course of the description of certain preferred embodiments thereof chosen to illustrate the principles of the invention. In the accompanying drawings which show such preferred embodiments,

FIGURE 1 is a side elevation of a sensitive relay, parts being shown in longitudinal vertical section;

FIG. 2 is an end View of the relay shown in FIG. 1, parts being shown in transverse vertical section;

FIG. 3 is a perspective view showing the armature and its mounting springs and the contacts;

FIG. 4 is a side elevation of the armature and its mounting, parts being shown in longitudinal vertical section;

FIG. 5 is a transverse sectional view on line 55 of FIG. 4;

FIG. 6 is a bottom plan view of the armature and its mounting springs;

FIG. 7 is a view partly in side elevation and partly in longitudinal vertical section showing a modified construction for attaching the springs to the armature; and

FIG. 8 is a horizontal sectional view looking down on the base plate and terminals.

Referring to the drawings in detail, there is shown an electromagnetic relay capable of opening and closing two sets of electrical contacts, each located at one end of the relay. The relay comprises a coil lit which may have a cylindrical magnetic core 12 extending therethrough and protruding beyond the ends thereof. At each end of the coil there is provided a large magnetic washer 14 which closely fits the core 12. The ends of core 12 are held by end pieces 16 which are L-shaped, being provided with in-turned horizontally extending portions 18. End pieces 16 have a bifurcated portion comprising a pair of tongues 2th which may be bent to slope toward each other slightly so as to tightly engage the core 12 and hold it captive. The use of the large Washers 14 engaging the surfaces of the end pieces 16 insures a magnetic joint of very high permeability.

A bar magnet 22 rests on the in-turned portions 13. The magnet is symmetrically polarized so that both ends have one polarity and the middle of the magnet is of the opposite polarity; for example, the ends may be N-poles and the middle of the magnet may be an S-pole. The armature 3b is in the form of a bar of magnetic material mounted on crossed iiexure springs 32.

A frame 34 which may be formed of non-magnetic metal is provided comprising two side plates having downwardly projecting legs 35 which are welded or otherwise secured to a metal base plate 36. At each end the frame 34 has a pair of cars 33 tightly engaging the end pieces to. The frame also includes a plurality of punch-outs it which extend inwardly into engagement with the magnet so as to hold it in position.

The springs 32 are anchored to terminal pins 42 which pass through and are supported by sleeves d4 of insulating material fitting in holes in the base plate 36, the pins being thus insulated from the metal base plate. A pair of terminal pins 42a are also carried by the base plate and are wired to the coil terminals. The springs 32 are secured to the armature 3% but electrically insulated therefrom. A preferred construction for this purpose comprises a molded block as of insulating material through which the springs pass and which is attached to the armature in any suitable manner, as by being molded over dovetailed projections 48 formed on the bottom of the armature. A suitable material for this purpose is a compound of mica and glass known under the commercial name of Mikroy. Other insulating materials having strength and rigidity may be used. The springs 32. are preferably continued through the insulating block 4i: and bent downwardly so as to form contact blades 50 which may carry contact buttons 52 for cooperation with the contact assemblies to be described.

Contact assemblies 54 are mounted at each end of the relay and, as shown, comprise terminal pins 56 passing through the base plate and carried by the insulating sleeves 44 and carrying upper and lower contact plates 58. Ohviously, instead of single contact plates 5%, spring pileups $9 (FIG. 7) of usual construction may be employed. The armature springs 32 have diagonal legs 6% which extend from their lower ends which are attached to the terminal pins 4-2 to the points 62 where they enter the block of insulating material 46. The springs 32 are offset laterally and longitudinally so that the points 62 lie in a common transverse axis which constitutes the effective pivot axis of the armature. As the armature pivots or tilts through an exceedingly small angle, it will be seen that the bending stresses to which the springs are subjected are very small and fatigue strain on the metal is negligible. Thus the armature is permanently pivotally mounted. in a practically frictionless manner.

As is clearly shown in FIG. 6, the block of insulating material 46 is preferably of a Z-shape so that each of the springs is carried by an oliset portion of the Z. The surfaces through which the portions of the springs enter the block are preferably bevelled, as indicated at 64, so as to be at right angles to the planes of the spring sections. The angularity of the springs of course may be varied to suit the needs of the design, but 45 is usually found to be a suitable angle.

The springs 32, being of thin but wide material, have the necessary flexibility to permit movement of the armature with the minimum resistance, but at the same time they are wide enough to have great stidncss in a lateral direction. Also, the use of the two springs side by side gives firm support to the armature against lateral displacement and enables the relay to withstand mechanical shocks. Furthermore, there are two springs, each connected to the armature, so that the connecting points, lying in a common axis, provide the armature with a substantially fixed axis about which it tilts. This provides for the tilting movement of the armature without substantial displacement longitudinally so that the magnetic paths at the ends of the armature are not displaced and reluctance characteristics remain constant. Furthermore, by locating the axis of rotation practically in line with the points where the springs emerge from the mounting block permits the axis of rotation to be located close to the center of gravity of the armature. v

Use of the springswhich support the armature and also are extended to form the contact blades results in an important manufacturing economy, as the mounting of the springs on the pins dzboth forms the basis of support for the armature and also establishes the electrical circuits to the contact arm's. Thus the number of connections which has to be made to the base of the relay is reduced and the total number of parts is reduced. The supporting of the armature entirely on the springs elimi nates all bearing pivots, ball bearings and the like, there by eliminating friction and Wear and further reducing the number of parts required in the assembly. Elimination of friction assures reliable snap action with the switch elements.

FIG. 7 shows a slight modification in the way of attaching the springs to the armature. In this instance a molded block of material need not be used, but the springs are attached to the under side of the armature by means of metalized ceramic blocks 66 which may be brazed to the metal parts.

I claim:

1. A relay comprising a coil, a magnetic core extending through said-coil, pole pieces in magnetic circuit with said core, an armature and means for movably mounting said armature with its opposite ends positioned to be respectively influenced by magnetic force in the adjacent pole piece, crossed fiexure pivot springs fixed to said armature, a contact member movable with said armature and in electrical connection with at least one of said flexure pivot springs, said relay having a base on which said flexure pivot springs are mounted, and electrical connections to the fiexure pivot spring electrically connected with said movable contact member.

- 2. A relay comprising a coil, a magnetic core extend ing through said coil, a pair of magnetic pole pieces magnetically influenced by said coil, a relay base, means for supporting said coil on said base, an armature and means for movably supporting said armature on said base in operative proximity to said pole pieces, said armature supporting means comprising crossed fiexure pivot springs mounted .on the base, said armature being fixed to said fiexurepivot springs near the axis in which said springs cross, electrical connections to said springs near their points of connection with the relay base, portions of said springs constituting movable contact elements, and fixed contact members with which said contact elements co operate on movements of saidfarmature.

3. A relay comprising a coil, a magnetic core extend ing through said coil, 21 pair of magnetic end pieces each having a po-lti'on engaging and holding one end of said core and having a flange at the lower end thereof, a permanent bar magnet supported on 'said flanges, said magnet having poles of the same polarity at its ends and a pole of the opposite polarity at-the middle thereof, a bar armature disposed below and extending along said magnet, a base for the relay, a pair of tiexure pivot springs mounted on said base at spaced points and sloping upwardly therefrom so as to cros's'ih an axis 'substam tially midway of the length of the armature, means for fixing the armature to said springs near the crossing axis thereof, said armature being electrically insulated from said springs, portions of the springs extending beyond their oints or connection with the sans-rare, and elec; trical contact assemblies 'inourlt'ed on 's'aidbase bel'ov. said magnet an srmamre in position to cooperatewith the extended end portions of said p gs 'npon move ment of said armature, and electrical connections to the ends of said flex'u're pivot springs mounted on saidbase',

4. A relay 'com'prising' a' coil, a pair of magnetic pore pieces magnetically influenced by said coil, a relay base, means for supporting said coil on said base, an arma ture and means for movably supporting said armature on said base with its respective ends in operative proximity to respective pole pieces, said armature supporting means comprising crossed fiexu'r'e pivot springs mounted on said base, the axis at which springs cross being near the center of the armature, said armature being fixed to said springs near said axis, fixed eontact elements on said base, movable contact elements, and connections firom said armature to said movable contact -element's for moving the same with respect to 'said fixed contact elements. 7

5. A relay as claimed in claim 4 in which a block of insulating material is mounted on the arm ture, said springs being embedded in said block so as to suppbrt the armature. I

6. A construction as claimed in claim 5 in which the ends of the springs not mounted on the base extend in opposite directions out of said block of insulating ma: terial and carry the contact elements cooperating with the fixed contact elements on the base. v 1

7. A construction as claimed in claim 6 in which the armature has a lug projecting therefrom and the block of insulating material is molded to said lug so as to secure the armature to said block of insulating material.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A RELAY COMPRISING A COIL; A MAGNETIC CORE EXTENDING THROUGH SAID COIL, POLE PIECES IN MAGNETIC CIRCUIT WITH SAID CORE, AN ARMATURE AND MEANS FOR MOVABLE MOUNTING SAID ARMATURE WITH ITS OPPOSITE ENDS POSITIONED TO BE RESPECTIVELY INFLUENCED BY MAGNETIC FORCE IN THE ADJACENT POLE PIECE, CROSSED FLEXURE PIVOT SPRINGS FIXED TO SAID ARMATURE, A CONTACT MEMBER MOVABLE WITH SAID ARMATURE AND IN ELECTRICAL CONNECTION WITH AT LEAST ONE OF SAID 